docs: def _create_request(self, verb, url, query_params=None, data=None, send_as_file=False):
          """Helper method to create a single post/get requests.
  
          Args:
              verb - MultiRequest._VERB_POST or MultiRequest._VERB_GET
              url - A string URL
              query_params - None or a dict
              data - None or a string or a dict
              send_as_file - A boolean, should the data be sent as a file.
          Returns:
              requests.PreparedRequest
          Raises:
              InvalidRequestError - if an invalid verb is passed in.
          """
  
          # Prepare a set of kwargs to make it easier to avoid missing default params.
          kwargs = {
              'headers': self._default_headers,
              'params': query_params,
              'timeout': self._req_timeout,
          }
  
          if MultiRequest._VERB_POST == verb:
              if send_as_file:
                  kwargs['files'] = {'file': data}
              else:
                  kwargs['data'] = data
              return PreparedRequest(partial(self._session.post, url, **kwargs), url)
          elif MultiRequest._VERB_GET == verb:
              return PreparedRequest(partial(self._session.get, url, **kwargs), url)
          else:
              raise InvalidRequestError('Invalid verb {0}'.format(verb))